Improvement in repeaters for duplex telegraphs



J. B. STEARNS.

Repeaters for Duplex Telegraphs.

Patented Jan. 14,1873.

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JOSEPH B. STEABNS, OF BOSTON, MASSACHUSETTS.

Specification forming part of Letters Patent No. 134,776, dated January14, 1873.

To all whom it may concern:

Be it known that I, JOSEPH B. STEARNS, of Boston, in the county ofSuffolk and Commonwealth of Massachusetts, have invented an Improvementin Telegraph Apparatus, of which the following is a specification:

In telegraphing on long lines between two stations at such a distanceapart that a current of sufiicient intensity to enable them to common tomake use of an apparatus at an intermediate station, which receives thesignals sent from one station and automatically retransmits them to theother station with additional battery force.

This apparatus is known as a repeater or translator; and my inventionconsists in an improved form, which repeats simultaneously to eachstation signals arriving from opposite stations on the same line-wire atthe same time.

I have previously patentedJune 2, 1868, Letters Patent Nos. 78,547 and78,548-apparatus for telegraphin g in opposite directions on the sameline-wire at the same time; and in my present invention I make use ofthis apparatus, so connecting two of them together at one station thatthey form a repeater.

The construction and operation of my double transmitting apparatus arefully described in the patents before referred to, but for the purposeof more fully explaining my present invention I will state briefly thatthe princi ple of its operation consists in preventing the relay at thesending station, though always in circuit, from responding to thesignals transmitted from that station by winding its electro-magnet withtwo coils in opposite directions, or by constructing said relay ofmagnets opposed to each other, and by dividing the current from thebattery into two branches, one of which passes through one coil or onemagnet of the relay to the line, and the other passes through the othercoil or other magnet to the earth, through a resistance-coil having thesame or nearly the same resistance as the line. When, therefore, thecircuit is closed at the sending-station these divided currentsneutralize each others effect upon the relay, and

it remains silent.

My repeating apparatus is arranged as follows: A is the receiving-magnetor relay of the line east, and A the receiving-magnet or relay of theline west. B is an electromagnet on the eastern side of the repeater,and which is in circuit of local battery L B, and whose armature-leveracts as a key to close the circuit from the main battery M B through thereceiving-magnet A. The circuit of L B is broken and closed by the leverof the western receiving-magnet A, and B is an electro-magnet on thewestern side of the repeater excited by the local battery L B, andsimilarly arranged as the magnet B with the receivingmagnet A of theline east. M B 0 a A c is the eastern circuit; and M B 0 a A b B E, theneutralizing branch circuit of the receiving instrument; M B o a A c thewestern circuit, and M B 0 a. A b R E, the neutralizing circuit of itsrelay; and m n, the western local circuit.

The operation of this repeater is as follows: When a signal istransmitted from the eastern station the eastern receiving-magnet A isexcited, the armature-lever falls against the contact 1), and the localcircuit m a is closed through the western local magnet B, its lever qfalls against the contact 0, the circuit of the main battery M B isclosed, and the signal retransmitted to the western station. Though thecircuit is closed through the magnet A it, however, fails to respond,owing to the division of the circuit, as before explained, and theneutralizing effect of the branch circuit A R E consequently its leverremains unmoved. Should, however, a signal be transmitted from thewestern station at the same time the balance between the neutralizingcnrrents circulating in the relay or receiving instrument A is disturbedby this increase of current strength in one wire of magnet A, and thearmature-lever is moved, thereby completing the local circuit at a,exciting the magnet B, and thereby transmitting the signal to the.eastern station by the main batteryM B. The two distant stations arethus enabled to communicate with each other simultaneously, both signalsbeing repeated at the same time at the intermediate station.

Any of the forms of double transmitting relays described in theabove-mentioned patthe electro magnets A A B B, and their ents, Nos.78,547 and 78,548, may be substitutcorresponding circuits, as andfor thepnrpose ed for the relays A and A. set forth.

What I claim as my invention, and desire JOSEPH B. STEARNS. to secure byLetters Patent of the United Witnesses: States, is- WILLIAM A. HAYES,J12,

The arrangement, in a duplex repeater, of O. E. CRANE.

